Magnetic fields around the earth are called geomagnetic fields. The measurement of marine geomagnetic fields is generally a process of geomagnetic measurement by sailing a ship carried with a magnetometer on the sea. At present, many measurements of marine magnetic fields are performed by dragging only. A magnetic probe is dragged in the seawater after a surveying ship, and the cable for dragging has a length which is three times greater than the length of the ship. This operating mode will be limited in some sea areas, for example, an inshore cultivation area, a polar area with floating ice, etc., in which case the magnetic probe will be damaged or even get lost.